Machine-to-Machine (M2M) Communication (Machine Type Communication: MTC)
A brief description will be given of M2M communication (or MTC).
M2M communication refers to communication between electronic devices, that is, between machines. While M2M communication means wired or wireless communication between electronic devices or between a human controlled device and a machine in general, it is used to refer to wireless communication between electronic devices, that is, between machines. M2M terminals used in a cellular network have poorer performance or capabilities than general terminals.
Many terminals are present in a cell and may be classified according to type, class, service type, etc.
For example, terminals can be classified into a terminal for human type communication (HTC) and a terminal for machine type communication (MTC). MTC may include communication between M2M terminals. HTC refers to signal transmission and reception according to determination of signal transmission by human, whereas MTC refers to signal transmission by terminals according to generation of event or periodically without human intervention.
When M2M communication (or MTC) is considered, the number of terminals may abruptly increase. M2M terminals may have the following features based on services supported thereby.
1. A large number of terminals in a cell
2. A small quantity of data
3. Low transmission frequency (M2M terminal may have transmission periodicity)
4. A limited number of data characteristics
5. Insensitive to time delay
6. Low mobility or fixed
M2M communication may be used in various fields such as protected access and monitoring, trace and discovery, public safety (emergency, disaster, etc.), payment (vending machines, ticket machines, parking meters, etc.), health care, remote control, smartmeter, etc.
Idle Mode
An idle mode is a mechanism in which a terminal can periodically receive a downlink broadcast message without registering in a specific base station even when the terminal moves in a wireless link environment in which a plurality of base stations is located throughout a wide area.
The idle mode is a state in which only downlink synchronization has been achieved such that all normal operations including handover (HO) are stopped and a paging message corresponding to a broadcast message can be received only in a specific period. The paging message instructs a terminal to perform a paging action. For example, the paging action includes ranging, network reentry, etc.
The idle mode may be initiated by a terminal or a base station. That is, the terminal can enter the idle mode by transmitting a deregistration request DREG-REQ message to the base station and receiving a deregistration response DREG-RSP message from the base station as a response to the deregistration request message. Otherwise, the base station can enter the idle mode by transmitting an unsolicitated deregistration response message DREG-RSP or a deregistration command DREG-CMD message to the terminal.
When the terminal receives a paging message directed thereto within an available interval (AI) in the idle mode, the terminal changes to a connected mode through a network reentry process with the base station to transmit/receive data.